[Libre-soc-isa] [Bug 532] discuss iterative approach for statistical analysis of effectiveness of Compressed PowerISA envofing

bugzilla-daemon at libre-soc.org bugzilla-daemon at libre-soc.org
Sat Nov 21 14:45:57 GMT 2020


https://bugs.libre-soc.org/show_bug.cgi?id=532

--- Comment #1 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
from aoliva

Here's a hack that adds 'histogram' as a ppc disassembler option.  It
makes separate buckets according to binutils' own notion of ppc opcodes.
I'm not sure that's the most useful way to go about it, but it ought to
do as a first cut.

I suppose counting significant bits of immediate and offset operands
could be useful, but I haven't implemented that yet.

I imagine that it might make sense to count branches in a single bucket.

Any other thoughts on what else would be useful to have?


$ ./objdump -M histogram -d ppc-gcc | sed '1,/^Opcode histogram/d' | sort -n |
tail
    3386 cmpdi (2c200000)
    4306 nop (60000000)
    4404 beq (41820000)
    5219 b (48000000)
    5715 bl (48000001)
    8957 li (38000000)
    9205 addi (38000000)
   10167 std (f8000000)
   10718 mr (7c000378)
   18828 ld (e8000000)

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